Method for producing a cigarette with low tar yield



April 30, 1968 a. P. TOUEY ETAL 3,

METHOD FOR PRODUCING A CIOARETTE WlTH LOW TAR YIELD Filed Feb. 15, 1966 TOBACCO TREATED WITH OVER 5 PERCENT SODIUM OR CIGARETTE WRAPPER POTASSIUM NITRATE PERCENT OF SALT ADDED TO TOBACCO FIG 2 GEORGE P- TOUE Y ROBERT C' MUMPOWER H INVENTORS WcQ/M ATTORNEYS United States Patent 3,380,458 METHGD FOR PRODUCING A CIGARETTE WITH LUW TAR YHELD George P. Touey and Robert C. Murnpower II, Kingsport,

Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Feb. 15, 1966, Ser. No. 527,457 6 Claims. (Cl. 13117) This invention relates to additives for smoking tobacco, and to smoking devices such as, for example, cigarettes made with tobacco containing such additives. More particularly, this invention concerns a new technique for substantially lowering the amount of tarv produced by a cigarette during smoking.

In the manufacture of the modern cigarette it is desirable to produce a product which will deliver a lowered amount of smoke condensate (tar) to the smokers. One way of accomplishing this is to equip cigarettes with filters. While filters are effective to some extent in this respect it is highly desirable to have another way of re du-cing the tar content of tobacco smoke, particularly a way which could be used either in addition to or in place of conventional tobacco smoke filters. Our invention provides such a way.

Cigarette tobacco is known to contain small amounts of nitrate salts. For example, it has recently been reported (Tobacco Science, IX, pp. 149-157, December 1965) that cigarette tobacco used in making cigarettes may contain as much as 0.58% nitrate nitrogen. However, this amount is too small to effect any substantial reduction in the amount of tar delivered by the cigarette as will be illustrated by the subsequent examples of this invention. Calculated in terms of the salt concentration this amount (0.58% N) represents only 3.5% NaNO or 4.2% KNO based on the dry weight salt-containing tobacco. The usual nitrogen content of a blended tobacco for cigarettes is less than 0.2%. As NaNO this would be less than 1.3% and as KNO it would be less than.1.4%. French Patent 1,180,320 teaches that when certain oxygen releasing substances are added to smoking products they reduce the amounts of polycyclic aromatic hydrocarbons formed in the smoke; This patent mentions the addition of a salt of an oxygenated acid of nitrogen to cigarette paper or tobacco, but the examples illustrate the addition of nitrite salts to the paper. The amounts actually added to the product are not mentioned. US. Patent 3,121,433 discloses the addition of potassium nitrate to reconstituted tobacco sheet to improve its burn characteristics. However, the amount in the sheet is only 3%. Bently and Burgan (The Analyst, 85, 727-30, 1960) describe adding several compounds to tobacco to cause a reduction in the amount of 3,4-benzopyrene formed in the smoke. They obtained positive results when up to of copper nitrate or up to 4% of potassium nitrate was added to the tobacco and negative results with other nitrate salts.

In none of the foregoing reports or patents is there any mention of addition of more than 5% of a nitrate salt to tobacco. The reduction of polycyclic hydrocarbons in cigarette smoke is no evidence that the smoke will be less harmful. On the other hand, a substantial reduction in tar delivered by a cigarette is a clearly desirable elfect.

Therefore, an object of this invention is to disclose a chemical additive for natural leaf smoking materials which will substantially reduce the total particulate matter (tar) normally produced when the material is burned.

Another object of this invention is to disclose a tobacco mixture containing a chemical additive for reducing the smoke condensate or tar produced when the tobacco is smoked.

Still another object of this invention is to disclose a nontoxic chemical additive for tobacco which will alter the burning characteristics of the tobacco in a manner "Ice that will decrease the amounts of smoke condensate or tar in the smoke.

Yet still another object of this invention is to disclose a cigarette which produces a reduced amount of smoke condensate or tar products in the tobacco smoke when smoked.

A further object of this invention is to disclose a method of treating a natural leaf smoking material for reducing the smoke condensate or tar products contained in the smoke that is produced when the material is smoked.

Yet still another object of this invention is to disclose a method of treating shredded tobacco with a chemical additive for decreasing the amount of smoke condensate or tar produced when the tobacco is smoked.

A still further object of this invention is to disclose a process for producing a cigarette which when smoked contains a reduced amount of tar in the tobacco smoke.

Another object is to disclose the use of sodium and/ or potassium nitrate, at certain minimum concentrations, as additives to tobacco for accomplishing the lowering of the amount of tar produced by a cigarette.

According to the present invention it has been found that substantial reduction in total tar yield is obtained by adding more than 5%, preferably 69% by weight, of a nitric acid salt to the tobacco, a result apparently not obtained in the prior art because of the use of lower amounts and other types of nitric acid salts.

While we do not wish to be bound by any theory of why our use of more than 5% of a nitrate tobacco additive is so effective in tar removal, it is thought that the thermal decomposition temperatures of nitric acid salts such as KNO and NaNO are such that they are decomposed at the temperature prevalent in the area immediately adjacent to the burning Zone Where most of the smoke condensate (tar) is being formed. In contrast, other salts are decomposed at lower temperatures and therefore are not present in sufi'icient amounts to be effective at the time that the moderately hot zone in which tar is formed reaches them, while others are so stable that they do not react in the moderately hot tar-formin zone, immediately behind the burning zone, but remain inert and therefore ineffective for tar reduction.

Further objects and advantages of this invention will be more apparent upon reference to the accompanying specification, specific examples, claims and drawings wherein:

FIGURE 1 illustrates the nitric acid salt treated smoking tobacco of this invention formed into a cigarette product; and

FIGURE 2 is a graph illustrating the relationship between the percentage of nitric acid salt added to a smoking tobacco and the reduction in the smoke condensate or tar products produced when the tobacco is smoked.

The nitrate salt additives contemplated by this invention can be incorporated into the tobacco or other natural leaf smoking material in any desirable manner. For example, solutions of the sodium or potassium nitrate salt additives in a suitable solvent, such as water, may be applied to the tobacco as by spraying, soaking, sprinkling or the like after which the solvent is driven off as a vapor leaving thead-ditive thoroughly incorporated with the tobacco. The nitrate sait additives may aiso be applied as a finely-divided solid material through a dusting, shaking or dispersing medium of any suitable type which will uniformly disperse the additive over the tobacco. The incorporation of the additive may take place at any time prior to the final packaging of the tobacco product. In the case of cigarette tobacco it may be incorporated before or after blending of the various tobaccos if, in fact, blended tobacco is employed, and the additive may be applied to one or all of the blend constituents.

The amount of additive in the final product contemplated by this invention is rather small, but the specific amounts employed is quite critical. Generally speaking, however, the desirable and totally unexpected substantial reduction of smoke solids or tar products can be obtained if the nitrate salt additive is incorporated into the final tobacco product in amounts of more than 5 percent to as high as 9 percent by weight (dry basis). However optimum reduction in the smoke solids or tar products in the tobacco smoke is obtained when about 6 to 9 percent of nitrate salt additive is used.

A further understanding of the invention will be had from a consideration of the following examples that may be used in actual commercial practice and are set forth to illustrate the sharp reduction in the amount of tar (smoke solids) produced by a cigarette as the amount of NaNO (or KNO added to it is increased.

EXAMPLES The tobacco was removed from 2,000 domestic cigarettes and was divided into 10 equal portions. One portion was treated with a very fine spray of water until the weight ratio of water to tobacco was 1.5:1. The wet sample was then spread out and dried in air to a uniform moisture content of 12 percent. Cigarettes 85 mm. in length and containing 1.1 gram of the tobacco were prepared and tested for pressure drop (resistance to draw). Only those having a pressure drop within a range of 3.0-3.3 inches of water were used in the smoking tests. They represented control cigarettes. This technique for determining the pressure drop of a cigarette has been described by Touey (Analytical Chemistry, 27, 1788-90 (1955) The nitrate nitrogen content of the control tobacco was 0.1 percent.

Other portions of the original batch of tobacco were sprayed with water solutions of sodium nitrate until the Jeight ratios of added liquid to tobacco was also 15:1. The concentration of NaNO in these solutions varied from 2 percent to 10.7 percent. The wet samples were spread out and dried to a uniform moisture content of 12 percent. Cigarettes of the general type illustrated in FIGURE 1, which were 85 mm. in length and containing 1.2 grams of tobacco calculated on a salt free basis, were prepared from these samples and screened for pressure drop. Only those having a pressure drop within the range of 3.0-3.3 inches of water were used in the smoking tests.

Other samples of the tobacco were treated with water solutions of KNO of increasing salt content in an identical manner. These were also dried to a moisture content of 12 percent and converted to cigarettes having a pressure drop of 3.0-3.3 inches and containin 1.2 grams of tobacco calculated on a KNO salt free basis.

Cigarettes from these various groups were automatically smoked on a smoking machine described by Mum- 0 power and Touey [Tobacco Science, 5, 31-35 (1961)]. Using a 35-ml. puff of 2-sec. duration at the rate of 1 pur'f/ minute, the machine smoked 5 cigarettes from each group to a butt length of 30 mm. The particulate phase of the smoke (tars) in each case was collected on a tarred Cambridge absolute filter situated directly in back of the cigarette. Then the filter was reweighed to obtain the wet weight of the tar collected. The tar on the filter was analyzed for moisture content so that a moisture free tar delivery value for each group of cigarettes smoked could be obtained. A new Cambridge filter assembly was used for each group of cigarettes tested. This method for collecting and weighing the total particulate matter (TPM) delivered by a cigarette has been described by Ogg [J. Assoc. Oi'lic. Agri. Chemists, 47, 356-62 (1964)] and the technique for determining the amount of water in the total particulate matter collected in this manner has been described by Sloan and Sublett [Tobacco Science, 9, 70-74 (1965)].

For illustration purposes the results of these examples are set out in Table 1 hereinbclow and in graphic form in FIGURE 2.

TABLE 1.AMOUNT OF TAR DELIVERED BY THE GARETTE Mg. Moisture Free Percent Reduction in Percent Added Type of Total Particulate 'lotal Particulate Salt in Tobacco Salt Matter Delivered/ Matter Due to the Cigarette Salt 0 (Control) None 26. 0 2. 26. 0 0

25.3 2. 7 24. 3 6. 5 24. 1 7. 3 5 0 NaNO; 23. O 9. 2 KNOs 23. 7 8. 9 6.1 NaNO; 19.0 26.9 KNOs 18. 8 27. 6 7.1. NaNO 18.0 30.9 KNO; 18. 3 20. 6 8.2 NaNOa 17.0 34. 7

KNO; NaNO 17 1 d4 1 KNOa 10.1 NaNO; 17 0 31.7 KNO; 17. 2 33. 8

These tabulated results show that there is a gradual increase in the reduction of the amount of total particulate matter delivered by the cigarette as the added salt concentration in the tobacco increases from 0 to 5.0 percent the highest reduction being slightly under 10 percent for the 5 percent salt level. However, there is a pronounced drop in the total particulate matter delivery when the salt concentration exceeds the 5 percent level. For example, when the salt concentration in the tobacco was increased from 4 percent to 5 percent the reduction in total particulate matter delivery over that of the control dropped from about 7 percent to about 9 percent, but when it was increased from 5 percent to 6.1 percent the drop in tar delivery reached about 27 percent. A further drop in the amount of total particulate matter delivered was obtained with higher concentrations of salt in the tobacco until a concentration of about 8 percent salt was added.

Under certain conditions it may be desirable to combine the sodium and potassium salts of nitric acid together and then treat the natural leaf smoking material with this mixture of nitric acid salts.

From the foregoing it will be readily apparent that the use of sodium or potassium salts of nitric acid as a tobacco additive of the type and in the quantity hereinabove described substantially reduces the amount of smoke condensate or tar products produced when the tobacco is smoked. Furthermore, not only is over a 25 percent reduction in the smoke condensate or tar products realized by using the nitric acid salt additives, but the additives are extremely easy to apply to natural leaf smoking materials by known techniques employing equipment already available to the tobacco industry. This coupled with the low cost of the additives themselves permits tobacco products containing the additives to be manufactured at a price competitive with existing commercial tobacco products.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. In a smoking product consisting essentially of natural tobacco leaf material, the improvement which comprises adding thereto 5.5 to 10 percent by weight of a nitric acid salt selected from the group consisting of the nitric acid salt of sodium, nitric acid salt of potassium, or mixtures thereof, said salt being intermixed with said leaf material for reducing at least partially the smoke condensate products produced when the leaf material is smoked.

2. A smokable product according to claim 1 in which the smokable product is in the form of a cigarette.

3. As a new article of manufacture, a natural tobacco leaf smoking material containing between 5.5 and 10 percent by weight of a nitric acid salt, said salt being selected from the group consisting of nitric acid-salt of sodium, nitric acid salt of potassium, or mixtures thereof.

4. The method of treating a natural tobacco leaf smoking material for reducing the amount of smoke condensate or tar products produced during the normalprocess of smoking same comprising applying thereto from 5.5 to 10 percent by weight of a nitric acid salt selected from the group consisting of nitric acid salt of sodium, nitric acid salt of potassium, or mixtures thereof.

5. The method of treating a natural lea-f smoking material according to claim 4 wherein the nitric acid salt is applied to the natural leaf smoking material in an aqueous solution which is then dried to leave a coating of the nitric acid salt on the natural leaf smoking material.

6. The method of treating a natural leaf smoking material according to claim 4 wherein from 8 to 10 percent by weight of the nitric acid salt is applied to the smoking material.

References Cited UNITED STATES PATENTS 2,007,407 7/ 1935 Sadtler 131-17 X 2,029,494 2/ 1936 Loewenthal 13 l17 X 2,131,160 9/1938 Avedikian 131-142 X 3,003,895 10/ 1961 Grunwald 13117 FOREIGN PATENTS 449,206 6/ 1948 Canada.

42,394 1888 Germany.

SAMUEL KOREN, Primary Examiner.

D. J. DONOHUE, Assistant Examiner. 

1. IN A SMOKING PRODUCT CONSISTING ESSENTIALLY OF NATURAL TOBACCO LEAF MATERIAL, THE IMPROVEMENT WHICH COMPRISES ADDING THERETO 5.5 TO 10 PERCENT BY WEIGHT OF A NITRIC ACID SALT SELECTED FROM THE GROUP CONSISTING OF THE NITRIC ACID SALT OF SODIUM, NITRIC ACID SALT OF POTASSIUM, OR MIXTURES THEREOF, SAID SALT BEING INTERMIXED WITH SAID LEAF MATERIAL FOR REDUCING AT LEAST PARTIALLY THE SMOKE CONDENSATE PRODUCTS PRODUCED WHEN THE LEAF MATERIAL IS SMOKED. 